The specific aim of this project is to evaluate the feasibility of developing novel fluorescent probes that utilize photoinduced electron transfer (PET) perturbation as a transduction mechanism. The primary challenge in developing effective fluorescent sensors/probes lies in the often mutually exclusive requirements of selectivity and sensitivity. Traditional approaches to sensor design have relied primarily on binding selectivity. Herein we propose the possibility of designing sensing molecules whose transduction mechanism is based on both binding and response selectivity. Importantly, the selective response will be obtained by the degree of perturbation caused by the binding event, not solely by the binding affinity. Thus, it may be possible to design sensors that bind to a series of analytes, but only one analyte elicits a fluorescence response, hence the term response selectivity. If successful the proposed sensors will undoubtedly fill a broad range of applications and we envision a significant impact in the development of new technologies for metabolomics research. Because our method is fundamentally based on fluorescence and molecular recognition, selectivity and sensitivity are inherent to the approach. This R15 proposal takes a specific approach that utilizes the combined expertise of the investigative team, which includes theoretical/computational, synthetic organic, and analytical chemistries. [unreadable] [unreadable] The following objectives will specifically test our hypothesis of response selectivity. Objective 1: Design and synthesize model sensors that are predicted to exhibit response selectivity based on preliminary experimental and computational studies. Objective 2: Characterize the photophysical properties of the sensors with various analytes under physiologically relevant conditions. Objective 3: Evaluate the efficacy of the proposed approach with regard to response selectivity versus binding selectivity. [unreadable] [unreadable] The full promise of genomics and proteomics can only be realized by the accurate measurement of metabolites with good temporal and spatial resolution (metabolomics/metabonomics). A significant problem lies in the fact that existing technologies are not capable of detecting endogenous metabolites of low abundance. Successful completion of this project will form the basis for future development of sensors for metabolites that are capable of transducing metabolite concentrations and flux sensitively and in real-time. Thus, the project has direct and immediate relevance to public health, most specifically the fundamental study of disease and the development of diagnostic equipment. [unreadable] [unreadable] [unreadable]